The present invention is directed toward a trailer lock and more particularly toward a tamper-proof locking assembly which is adapted to securely close the door of a truck trailer. While the invention was originally designed for this purpose, it is also useful for securing the door of a freight container, garage or substantially any other similar structure.
As is well known in the art, truck trailer doors must normally be securely locked closed in order to prevent unauthorized entry. This is necessary to prevent theft of merchandise being carried by the truck when the same is parked. A similar problem exists with construction trailers which may be left unattended overnight at a construction site. Such trailers are frequently used to store supplies and equipment.
Such trailers are normally provided with closure mechanisms such as an elongated vertically movable rod carried by the movable door which is adapted to cooperate with an opening in the door frame. Other types of closure mechanisms are also utilized. In most cases, however, the closure mechanism is locked into the closed position by a simple padlock which is passed through a pair of aligned hasps. However, these padlocks are normally totally exposed and can be easily and quickly removed utilizing a hacksaw, hammer or other tools.
There have been proposals set forth in the past to provide a means for guarding or protecting the locks for trailer door closures. Devices of this type are shown, for example, in U.S. Pat. Nos. 3,334,933; 3,736,016; 4,300,369 and 4,307,904. In each of these patents, however, the device is comprised essentially of a housing or other mechanism which is mounted on the exterior face of the door. Thus, with a sledgehammer or other tool, it would appear to be possible in most cases to remove the protective device by destroying the same.
U.S. Pat. No. 3,334,933 shows a second embodiment of a locking device which could be used with a trailer door or the like which is mounted essentially within the door so that substantially no part of the device extends beyond the outer surface thereof. However, in this embodiment of the device, the keyhole of the padlock is readily and easily exposed through an opening thereby making it possible to either pick or otherwise destroy the lock utilizing a screwdriver or other tool.